The first thing you need to do is partition your hd. I am by no means a linux guru. For several years I have used a partitioning system that has served me well. I create a 10 gb partition for each distro (this will be /). I created only one swap partition that is double the amount of ram that is on my system. Then I create large /home partition that will figure out to be at least 10 gb for each distro to be installed(could be more- whatever you desire). Then leave some unallocated space that could be moved to increase the size of any partitions that need it later. Hope this helps. Read up on partitioning before starting.

It might be easiest to use a GUI as well to space out your partitions.
both gparted and parted magic have been recommended often on these and other Linux forums, although I don't have personal experience with them.

You'd probably need to resize the main partition if you have only one.

I like Gparted for Linux
you can partition through a Linux setup or from within Linux

In case you have one partition, you can resize it to the size you think suitable and use the rest of the space to use how you see properly.

Then you could create the Linux main partition type ext4 with the mount point of "/"
and another partition for the swap space called Linux-swap and give it double the amount of RAM you have got, but it's up to you. Only one swap partition is needed even if you install multiple distributions.

If you have also Windows installed, and you want your files visible on Windows as well Linux, you can create a NTFS partition too and place there things like downloads and multimedia files.

1. Use Gparted and change the partition table to GPT. "Device > Create Partition Table..."
2. Make a small 2-3MB partition in the very beginning. Some hardware/distros require this specialized "boot-space".
3. Make a partition for each Linux distro and label it with the name of the desired distro (this is for better organization)
4. Format each partition with the desired filesystem
5. With the remaining space, make a partition that will be "/home/". This allows you to have the same personal files and settings in each distro.
6. Make a partition for other miscellaneous files if you wish.
7. Make two swap partitions that are each equal to the size of your memory. This offers better performance than having one the size of twice your memory.

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